1. Field of the Invention
The present invention relates to an arrangement for mounting an electronic control unit on an internal combustion engine.
2. Description of the Related Art
Conventionally, an electronic control unit adapted to control a fuel injection system for an engine, a turbocharger or an EGR (exhaust gas recirculation) unit is located in a passenger compartment.
In recent years, however, the electronic control unit is often located in an engine room because it is preferred in terms of layout. One example of such layout is disclosed in Japanese Patent Application Laid-Open Publication No. 7-293269 published on Jul. 11, 1995; the electronic control unit is mounted on an intake air pipe. Another example is found in Japanese Utility Model Application Laid-Open Publication No. 63-113764 published on Jul. 22, 1988; the electronic control unit is attached to a throttle body fitted in the intake air pipe.
Since the vicinity of the intake air pipe is not a severe environment thermally, mounting the electronic control unit on the intake air pipe is appropriate.
However, the intake air pipe does not have high rigidity so that it is not an optimum element for supporting the electronic control unit. In particular, when an intake manifold is manufactured from resin to reduce a total weight of the engine and the electronic control unit is mounted on the intake air pipe, the weight of the electronic control unit is supported on the intake manifold via the intake air pipe. The intake manifold having relatively low rigidity cannot bear such weight and therefore it deforms. Further, when the EGR valve or PCV (positive crankcase ventilation) is attached to the intake air pipe, additional weights act on the intake manifold.
An object of the present invention is to overcome the above described problems.
According to one aspect of the present invention, there is provided an arrangement for supporting an electronic control unit in an engine room (more specifically, on an internal combustion engine), characterized in that the electronic control unit is provided to bridge a part of an engine main body assembly and a part of air intake assembly. The engine main body assembly may include a head cover, a cylinder head, and a cylinder block, and preferably the part of the engine main body assembly is the head cover. The air intake assembly may include an intake manifold and an intake air pipe, and preferably the part of the air intake assembly is the intake air pipe. Therefore, the weight of the electronic control unit is partly supported by the engine main body assembly of which rigidity is high.
Preferably, the electronic control unit is inclined towards the engine main body assembly so that a larger ratio of the weight of the electronic control unit is supported by the engine main body assembly.
Preferably, a frame-like bracket may be provided to span the part of the engine main body assembly and the part of the air intake assembly, and the electronic control unit may be located on the frame-like bracket.